This application claims the benefit of Korean Patent Application No. 2001-11617, filed on Mar. 7, 2001, which is hereby incorporated by reference as if fully set forth herein.
1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a stereoscopic liquid crystal display device using a liquid crystal polymer film and fabricating method thereof.
2. Discussion of the Related Art
In normal vision, human eyes perceive views of the world from two different perspectives due to their spatial separation. The spatial separation between typical eyes is about 65 mm. In order to assess the distance between objects, the brain integrates the two perspectives obtained from each eye. In order to provide a display, which is effective in displaying three-dimensional (3-D) images, it is necessary to recreate this situation to the observer. That is, supplying a so-called xe2x80x9cstereoscopic pairxe2x80x9d of images to the observer""s eyes.
The technology expressing the 3-D images can be divided according to the display method, the viewpoint, whether or not the glasses are adopted, the structure of the system, and the condition of observation. Especially, the 3-D displays using the parallax between the right and left eyes may be classified into two types according to whether or not the glasses are adopted: stereoscopic displays and autostereoscopic displays. Stereoscopic displays have polarization type and time division type. Autostereoscopic displays have barrier type and lenticular type.
Stereoscopic displays typically display both of the images over a wide viewing area. The views are encoded by color, polarization state, and time of the display. A filter system of glasses worn by the observer separates the views; thereby each eye sees only the view that is intended for it. That is, the right and left eyes have different views.
Autostereoscopic displays present a spatial image to the viewer without the use of glasses, goggles or other viewing aids. Instead, the two views are only visible from defined regions of space. A xe2x80x9cviewing regionxe2x80x9d is a term described as the region of space in which an image is visible across the whole display active area. If the observer is situated such that one eye is in one viewing region and the other eye is in the other viewing region, then a correct set of views is seen and a 3-D image is perceived by the observer. In autostereoscopic displays, an image splitter and a cylindrical lens array is combined in the conventional display device.
Stereoscopic displays can be divided into anaglyph type, concentration difference type, polarizing filter type and LCD shutter type. In anaglyph type, red and blue or red and green filters are used for the right and left lenses of the glasses, respectively. In concentration difference type, filters whose transmittances are different from each other are used for the right and left lenses of the glasses. In polarizing filter type, optical principle is used for the 3-D projection. In LCD shutter type, the right and left lenses of the glasses are alternatively shut and simultaneously, the images for the right and left eyes are alternatively displayed.
Especially in the stereoscopic displays of polarizing filter type, a polarizing plate is formed on the surface of the display, thereby light parallel to the transmission axes of the polarizing filters of the right and left lenses, respectively, is emitted. The transmission axis of the polarizing filter is called the polarization axis. The polarizing plate has a plurality of micro-polarizing plates whose polarization axes are parallel to the corresponding polarization axes of the polarizing filters of the right and left lenses. Since light emitted from the plurality of micro-polarizing plates are received by the right and left lenses of the glasses respectively, the 3-D images are perceived by the binocular parallax of the viewer.
FIGS. 1A and 1B are perspective views of polarizing plates attached to a stereoscopic device of a conventional polarizing filter type and FIG. 1C is a perspective view of conventional polarizing glasses.
In FIGS. 1A to 1C, polarizing plates xe2x80x9cAxe2x80x9d and xe2x80x9cBxe2x80x9d are composed of a plurality of micro-polarizing plates 32a and 32b whose polarization axes are parallel to the corresponding polarization axes 33a and 33b of the polarizing film attached to the right and left lenses of the polarizing glasses 30 in mosaic and stripe shapes, respectively. The polarizing plates xe2x80x9cAxe2x80x9d and xe2x80x9cB,xe2x80x9d having a plurality of micro-polarizing plates 32a and 32b, are formed through fabrication processes of FIGS. 2A to 2F.
FIGS. 2A to 2F are schematic cross-sectional views showing fabrication processes of a conventional polymer polarizing film taken along a line IIxe2x80x94II of FIGS. 1A and 1B.
In FIG. 2A, a plurality of first micro-polarizing regions xe2x80x9cCxe2x80x9d and second micro-polarizing regions xe2x80x9cDxe2x80x9d are defined on an entire surface of a substrate 34.
In FIG. 2B, a polymer polarizing film 36 having a first polarization axis 38a is formed on the substrate 34. Generally, the polymer polarizing film 36 is made by adsorbing iodine (I) or dichromatic dyes into one-directionally elongated poly vinyl alcohol (PVA) film. Here, a transmission axis of the polarizing film, i.e., a polarization axis is perpendicular to the elongated direction of the PVA film. In ambient light, only linearly polarized light parallel to the polarization axis of the polarizing film is transmitted.
In FIG. 2C, after forming a photoresist (PR) layer 39 on the polymer polarizing film 36, an exposure process is performed with a mask 40 over the polymer polarizing film 36. The mask 40 has a plurality of transmission regions xe2x80x9cExe2x80x9d and a plurality of shield regions xe2x80x9cFxe2x80x9d. The PR is divided into positive type and negative type. For the positive type, the PR of the exposed region is removed by the developing solution. For the negative type, the PR is not removed. In this description, the case using the PR of the positive type is explained. That is, the mask 40 is disposed over the substrate 34 so that the plurality of shield regions xe2x80x9cFxe2x80x9d corresponds to the plurality of first micro-polarizing regions xe2x80x9cCxe2x80x9d.
In FIG. 2D, after developing, a PR pattern 39a is formed only at the plurality of first micro-polarizing regions xe2x80x9cCxe2x80x9d.
In FIG. 2E, the polymer polarizing film of the plurality of the second micro-polarizing regions xe2x80x9cDxe2x80x9d is etched by, for example, a chemical etching method (water:ethyl alcohol=30%:70%), photochemical etching method, excimer laser etching method or reactive ion etching method. Then, the PR pattern 39a on the plurality of first micro-polarizing regions xe2x80x9cCxe2x80x9d is removed by the stripper. Through this photolithography process, a first polarizing film 43 having a plurality of first micro-polarizing plates 42a at the plurality of first micro-polarizing regions xe2x80x9cCxe2x80x9d is formed.
In FIG. 2F, a second polarizing film 45 having a plurality of second micro-polarizing plates 42b at the plurality of second micro-polarizing regions xe2x80x9cDxe2x80x9d is formed on another substrate 40 by repetition of processes of FIGS. 2A to 2E. The polarization axis 38b of the second polarizing film 45 is perpendicular to the polarization axis 38a of the first polarizing film 43 on the plane parallel to the substrate.
In FIG. 2G, a polymer polarizing film 47 having the plurality of first and second micro-polarizing plates 42a and 42b whose polarizing axes 38a and 38b are perpendicular to each other is formed by attaching the first and second polarizing films 43 and 45.
The polymer polarizing film 47 can be fabricated by other methods, and one example of a fabrication method will be explained as follows.
FIGS. 3A to 3E are schematic cross-sectional views showing other fabrication processes of a conventional polymer polarizing film.
In FIG. 3A, through exposure and developing processes, a PR pattern 39a is formed on a PVA film 36 at a plurality of first micro-polarizing regions xe2x80x9cCxe2x80x9d as in FIG. 2D.
In FIG. 3B, the polymer polarizing film 36 of exposed region 37 between the PR pattern 39a is bleached. That is, to eliminate the polarization property of exposed region 37 of the polymer polarizing film 36, the exposed surface of the polymer polarizing film 36 is treated by a caustic solution such as potassium hydroxide. The caustic solution, i.e., the bleaching solution can eliminate the dichromatic effect of the PVA film so that light is not polarized at the bleached region.
In FIG. 3C, after removing the PR pattern 39a by the etchant, a first polarizing film 48 composed of a plurality of first micro-polarizing plates 42 having a first polarization axis 38a and a plurality of first bleached regions 37 is formed.
In FIG. 3D, by depositing the PVA film on another substrate 46 and repeating the processes of FIGS. 3A to 3C, a second polarizing film 54 composed of a plurality of second micro-polarizing plates 50 having a second polarization axis 38b and a plurality of second bleached regions 52 is formed. The second polarization axis 38b of the plurality of second micro-polarizing plates 50 is perpendicular to the first polarization axis 38a (of FIG. 3C) of the plurality of first micro-polarizing plates 42 (of FIG. 3C). Furthermore, the plurality of second micro-polarizing plates 50 and the plurality of second bleached regions 52 are disposed at the second polarizing region xe2x80x9cDxe2x80x9d and the first polarizing region xe2x80x9cC,xe2x80x9d respectively.
In FIG. 3E, the first and second polarizing films 48 and 54 are attached to obtain the polymer polarizing film 56. Since the first micro-polarizing plate 42 of the first polarizing film 48 corresponds to the second bleached region 52 of the second polarizing film 48, the attached polymer polarizing film 56 is composed of the plurality of first and second micro-polarizing plates 42 and 50 whose polarization axes are perpendicular to each other. Each micro-polarizing plate 42 and 50 can be formed in a mosaic or stripe shape.
However, the fabricating method of a polarizing plate using a polymer polarizing film such as PVA includes the process of forming individual polarizing films corresponding to right and left lenses of glasses and the process of attaching individual polarizing films. Therefore, the fabricating process of the polarizing plate is too complicated and the production yields are decreased due to the increased cost.
Accordingly, the present invention is directed to a stereoscopic liquid crystal display device that substantially obviates one or more of problems due to limitations and disadvantages of the related art.
An advantage of the present invention is to provide a stereoscopic liquid crystal display device that uses a liquid crystal polymer film instead of a conventional polymer polarizing film, and fabricating method thereof.
Another advantage of the present invention is to simplify the fabricating process and to improve the production yields due to the reduced cost.
Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a stereoscopic liquid crystal display device includes: first and second substrates facing and spaced apart from each other; a liquid crystal polymer film having first and second micro-polarizing regions on an inner surface of the first substrate, polarization axes of the first and second micro-polarizing regions being different from each other; a first polarizing plate on the liquid crystal polymer film; a common electrode on the first polarizing plate; a second polarizing plate on an outer surface of the second substrate; a switching device on an inner surface of the second substrate; a pixel electrode connected to the switching device; and a liquid crystal layer interposed between the common electrode and the pixel electrode.
In another aspect, a fabricating method of a stereoscopic liquid crystal display device includes: preparing first and second substrates, the first substrate having first and second surfaces, and the second substrate having third and fourth surfaces; forming a liquid crystal polymer film on the second surface of the first substrate; exposing a first micro-polarizing region of the liquid crystal polymer film to light with a first exposure condition, thereby the first micro-polarizing region having a first polarization axis; exposing a second micro-polarizing region of the liquid crystal polymer film to light with a second exposure condition, thereby the second micro-polarizing region having a second polarization axis; forming a first polarizing plate on the liquid crystal polymer film; forming a common electrode on the first polarizing plate; providing a second polarizing plate on the fourth surface of the second substrate; forming a switching device on the third surface of the second substrate; forming a pixel electrode connected to the switching device; attaching the first and second substrates, the second surface of the first substrate and the third surface of the second substrate facing and spaced apart from each other; and forming a liquid crystal layer interposed between the common electrode and the pixel electrode.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.